1. Field of Invention
This invention relates to a method of controlling a servomotor for driving various machines such as a robot and a machine tool, and more particularly, to a sliding mode control.
2. Description of the Related Art
A variety of sliding mode control techniques are used for controlling servomotors in various machines to improve disturbance suppressing ability and achieve good follow-up with respect to commands. Such sliding mode control techniques are disclosed, for example, in Unexamined Japanese Patent Publications No. 2-297611 and No. 3-118618.
These conventional sliding mode control techniques, however, have no relevance to P control (proportional control) for a position loop or to PI control (proportional-plus-integral control) for a speed loop, which have conventionally been employed for controlling servomotors. Thus, conventional linear control techniques elaborated for the P and PI controls cannot be utilized at all for the control of a servomotor.
Thus, the application of the sliding mode control has been hindered mainly due to that the selection of various parameters is so time consuming and some other reasons.